Author(s): PAUL, S., DONATH, L., HOPPSTAEDTER, J., HECKSTEDEN, A., Institution: GERMAN SPORT UNIVERSITY COLOGNE, Country: GERMANY, Abstract-ID: 811

INTRODUCTION:
The glucocorticoid induced leucin zipper (GILZ) is a protein originally described as an anti-inflammatory regulator of gene expression in lymphatic tissue (1). Since then, expression of GILZ has been identified in a variety of tissues. This includes skeletal muscle where it has anti-myogenic effects and mediates the well-known muscle-related side effects of glucocorticoids but also of statins (1). Interestingly, recent evidence suggests that GILZ expression is also regulated by physical exercise with muscular, as opposed to cardiocirculatory strain, being the decisive factor (2). To verify these seminal findings, we performed a retrospective analysis of datasets from acute exercise trials published in Gene Expression Omnibus (GEO).
METHODS:
We conducted a systematic search of the GEO repository for gene expression studies reporting the acute effects of either endurance, conventional resistance, or eccentric resistance exercise. Gene expressional data was required to be quantified either via micro array or high throughput sequencing techniques. Only studies on healthy adults were eligible. Additionally, muscle biopsies must have been obtained acutely (3-6h) post exercise. Within-trial robust scaling of raw data was used to account for variation between trials. ANOVA and post hoc testing were used to compare changes in GILZ expression from pre- to post-exercise between groups.
RESULTS:
A total of 14 studies and 258 subjects (213 male; 45 female) could be included into the analysis. Activity level ranged from sedentary to endurance trained, and the age of examined individuals ranged from 18 to 90 years (35.2 ± 2.8 [mean ± SD]). Eccentric exercise resulted in the greatest downregulation of GILZ (- 0.56 ± 0.92 [AU]), closely followed by resistance exercise (- 0.46 ± 1.07 [AU]), and little change in GILZ expression was observed with endurance exercise (- 0.1 ± 0.93 [AU]).
CONCLUSION:
Our results support the hypotheses that mechanical strain is a key mediator of training induced changes in GILZ expression. It is noteworthy that this result has been obtained despite the substantial differences in age, level of habitual exercise, and exercise dose across studies.

1. Hoppstaedter J, Valbuena Perez JV, Linnenberger R, et al. The glucocorticoid-induced leucine zipper mediates statin-induced muscle damage. FASEB J. 2020;34(3):4684-4701. doi:10.1096/fj.201902557RRR
2. Hecksteden A, Hoppstaedter J, Bizjak DA, et al. Effects of acute exercise and training status on glucocorticoid-induced leucine zipper (GILZ) expression in human skeletal muscle. J Sci Med Sport. 2023;26(12):707-710. doi:10.1016/j.jsams.2023.10.007